Apparatus for handling solids material



Sept. 18, 1956 H. SCHUTTE 2,753,515

APPARATUS FOR HANDLING SOLIDS MATERIAL Filed June 23, 1953 3 Sheets-$heet 1 7777 INVENTOFQ Am dagmsffifeiziy Sc/zwtte BY l "3 18, 1956 sc u- E 2,763,515

APPARATUS FOR HANDLING SOLIDS MATERIAL Filed June 23, 1955 5 Sheets-Sheet 2 INVENTO Sept. 18, 1956 A. H. SCHUTTE 2,763,515

APPARATUS FOR HANDLING soLIns MATERIAL Filed June 25, 1953 5 Sheets-Sheet 3 i A Z United States Patent 2,763,515 APPARATUS FOR HANDLING SOLIDS MATERIAL August H. Schutte, Hastings-on-Hudson, N. Y., assignor to The Lumrnus Company, New York, N. Y., a corporation of Delaware ApplicationJune 23, 1953, Serial No. 363,607 2 Claims. (Cl. 302--53) This invention relates to improvements in the handling of sub-divided solids material and particularly to the transfer of such material by gases or vapors between zones of difierent pressures. This application is a continuationin-part of my copending application, Serial No; 90,026, filed April 27, 1949, and entitled, Method and Apparatus for Handling Solids Material, now abandoned.

In the conversion of hydrocarbons, as for example by catalytic cracking or continuous coking, it has been found desirable to transfer large quantities of solid contact material such as catalyst or coke in a closed circuit between zones at different pressures and at different vertical elevations. For the very fine dust-like materials of the order of 100 to 200 mesh particle size, the aerated manometric or fluidized technique has been developed. Larger particles, having average particle sizes in the range of 40 mesh to /2 inch, do not lend themselves satisfactorily to this type of transport due to attrition and excessive requirements for transporting or carrying vapor. These latter materials have been handled by mechanical elevators or by low differential pressure vapor lifts employing a relatively small concentration of solids in the ascending leg. Conveying of these materials by mechanical elevators has been done successfully but the equipment is costly in installation and maintenance.

The designer of continuous vapor lifts for the larger particle size material must limit the net upward velocity of the solids particles in order to avoid undue attrition and he must limit the percentage of solids in the lift leg in order to minimize the required pressure at the bottom of the lift leg. A high differential pressure between the vessel from which the solids material is being Withdrawn and the bottom of the lift leg would require an excessively long vertical seal leg to dissipate the differential pressure While still permitting downward flow of solids into the base of the seal leg. Since non-turbulent seal legs require about five feet in height to overcome one pound per square inch differential pressure, it follows that a pound differential pressure across the solids inlet seal leg will require a 50 foot vertical height for the seal leg. This in turn means that the bottoms outlet of the lowest process vessel must be at least 50 feet above grade. This not only increases the vertical height through which the solids must be elevated but also increases the overall height of the process unit and adversely effects the design of the supporting and structural members. The above difficulties are multiplied to an absurd degree when bottom lift leg pressures of 20 to 80 pounds per square inch are required for operation in conjunction with reaction vessels operating at approximately five pounds per square inch;

The result of the above limitations is that the vapor lift for commercial units must be designed for a low bottom pressure in the order of five to ten pounds per square inch gauge. Since the bottom pressure mustbe greater than theweight of the vertical column in transport, it is neces- 2,763,515 Patented Sept. 18, 1956 sary with conventional designs to use a low solids leading or low percent of solids per cubic foot, in the lift leg.

In such case, large volumes of lifting vapors must be handled at relatively high velocity and in commercial operations difficulties with particle attrition and equipment erosion may be expected. Furthermore, as all of the commercial solids contact materials have considerable variation in individual particle size and particle density, the lift must be designed with sufficient vapor velocity to maintain a moderate upward velocity for the heaviest and largest particles; otherwise elutriation will occur and the lift leg will choke up with an accumulation of maximum size particles. With velocity suflicient to carry the largest and heaviest particles the smaller and/or lighter particles will be moving considerably faster than the large critical particles and they will, therefore, collide with the larger particles, and by deflecting from the Wall of the lift leg, traverse and retraverse the stream; resulting in attrition and particle erosion. This situation becomes more serious as the gas velocity is increased and the particle density in the lift leg is decreased, thus increasing the relative velocity of the particles and increasing their travel between collisions.

it is one of the broad objects of this invention to improve the vapor lift handling of solids contact or catalytic materials by designing the equipment in such manner that the pressure conditions at the bottom of the lift leg may be completely independent of the pressure in the processing vessels; thus permitting optimum design for both the processing and solids conveying zones.

It is a further object of the invention to improve ethciency and operation of vapor lifts for granular solids materials by providing a cyclically operated sealing valve for positive sealing of the pressurized lifting chamber during the lifting operation, and the free opening into the chamber for gravity flow of the solids to fill the chamber.

Further objects and advantages of the invention will appear from the following description of a preferred form of embodiment thereof taken in connection with the attached drawing in which:

Fig. 1 is an enlarged vertical cross section of the bottom of a lift leg and the lifting chamber showing the operating and control devices.

Fig. 2 is a diagrammatic view of a continuous cyclic. contact system.

Fig. 3 is a partial elevation of a modified form of continuous cyclic contact system.

Fig. 4 is a substantially vertical cross a part of a control valve.

Fig. 5 is a horizontal cross section taken substantially along the lines 5-5 of Fig. 4.

Fig. 6 is a part elevation and part vertical section through a multiple valve construction.

Referring to Fig. l, granular solids material is supplied to solids inlet line 16 from a reservoir or vessel and its gravity flow into vessel 10 is controlled by valve 18. Line is and the process vessel connected to it will normally be under considerably lower pressure than that required to lift the solids material up the lift leg 12 by the action of lifting vapor introduced through valve 26 and vapor line 14 into vessel 16.

The cycle for the lifting device is as follows: 10 contains an inventory of solids toms of lift leg 12. With valve 42 opens valve 26 in the lifting vapor inlet 14 and introduces high pressure lifting vapors into vessel 10 at a controlled rate. As the internal pressure of vessel It) increases, the slidable member 20 of valve 13 .is driven back against its seat, effectively preventing back flow of lift vapors through line 16. The increase in pressure is accompanied by how of vapors down through the solids section through 18 closed, timing device bed in vessel and up the lift leg 12 until sufficient pressure and velocity has been obtained to entrain and lift solids material. As this lifting action continues, the inventory in vessel 10 decreases and when the level of solids has dropped to a suitable point, but preferably before the vessel is completely evacuated of entrainable solids, the level detecting device 28 detects this condition and through control 29, sets into operation timer 42 which closes valve 26, Shutting off the supply of lifting vapors. The level detecting device 23 and control 29 may be of the radio active type such as the Gagetron control now available commercially or other types which will detect the presence of solid material at an appropriate level by a property of the material other than its weight and independent of the pressure within the vessel.

With no further supply of lifting vapors the vapor fiow up the lift leg 12 rapidly decreases until the pressure at the top and bottom of this leg are equalized at a pressure far lower than that prevailing during the lifting operation and essentially equal to the pressure in solids supply line 16. The timer 42 after this short delay, then opens valve 18 by actuating operating mechanism 24 in turn withdrawing valve arm 22; leaving valve 26 closed. The solids material then enters the vessel and fills it to a fixed height which may be conveniently set by the natural flow angle of repose of the solids material. Timer 42 then closes valve 18 and the cycle is repeated.

Valve 18 is so constructed that the movement of the slidable member in closing the valve is a movement through a free pile or cone of repose of the solids material at a section where the solids are free to move laterally out of the way of member 20. This prevents jamming of the valve mechanism, crushing the solids particles, or difirculty in valve operation due to accumulation of fines in the guiding ways (not shown) for the slide member 20.

It will be appreciated that, if the valve were located in a closed conduit, which is always full of gravity packed particles it would be impossible to move the valve rnember 20 into the column of particles in the line, since the particles would be prevented by their natural arching tendency from moving out of the way. The valve 18 shown in Fig. l is a preferred design but other types of valves may be used if they satisfy the above conditions.

If it is desired to control the rate of flow of solids material into the vessel during the filling cycle, suitable stops or travel limits may be set in actuator 24 to obtain any reasonable filling time.

The application of the lifting and sealing devices to a variety of industrial operations may be accomplished. As an example, the application to a petroleum conversion operation such as catalytic cracking, coking, or pyrolysis is shown in Fig. 2. In the case of catalytic cracking the solids material handled would be active cracking catalyst of the type well known in the art. In the case of hydrocarbon coking or pyrolysis the solids material may be coke produced in the process or an inert refractory material. In these processes it is usual to recirculate the solids material at rates of 100 to 1,000 tons per hour through reaction or regeneration vessels which may be separate or may be combined in one shell as shown diagrammatically by vessel 38. Lifting heights of 100 to over 200 feet are usual and with high solids loading in the lift leg, a bottom pressure in the lift leg is required which is high compared to the pressure existing in the process vessel. By utilizing the intermittent lifting principle of this invention and completely sealing off the bottom of the lift leg from the process vessel during the lifting cycle while allowing the pressures to equalize before the solids filling cycle, the necessity for extensive seal legs or other continuous sealing devices operating under high differential pressure and subject to severe erosion is eliminated.

In this case vessel 38 diagrammatically indicates a chamber comprising one or more zones designed for hydrocarbon conversion and solids reconditioning as by regeneration or reheating. The solids material from the bottom of vessel 38 is delivered by lines 16 and 16a to two intermittent pressure lift chambers 10 and 10a under the control of valves 18 and 18a. The lifts 12 and 12a operate as described above in the description of Fig. l delivering the material to a disengaging hopper 35 supported at an elevation suitable for gravity discharge of the solids into the top of vessel 38 through line 37.

Control of the solids concentrations and velocity in the lifting legs 12 and 12a may be obtained by manipulating the adjustable baffles 36 and 36a to adjust the spacing of these baffles above the top of the lift legs; thereby varying the gas flow resistance to the flowing particles streams in reversing their direction and dropping down into hopper 35. The solids material normally flows out of hopper 55 into line 37 through valve 43 which may conveniently be designed or adjusted to maintain a constant flow of solids into vessel 38. The lifting vapors after disengaging from the solids in the hopper 35 are withdrawn through line 40 thru valve 41 which may be conveniently actuated by a conventional instrument to maintain an essentially constant pressure in hopper 3S and vessel 38.

For purposes of simplicity the hydrocarbon charge connections and other connections to process vessel 38 have been omitted.

The following example will show the advantages of utilizing the automatic intermittent sealing and lifting device described above. If we assume the case of a catalytic cracking unit requiring the circulation of 600 tons per hour of /8 inch spherical catalyst with a vertical lift height of 140 feet using conventional mechanical elevators of pressure tight construction designed for a solids temperature of 900 to 1,000 B, it will require four elevators having six foot diameter casings. The material cost for these elevators will be greater than the material cost for all of the other equipment in the catalytic cracking section of the plant.

If a steam lift were employed, designed for only 10% solids concentration in the lift leg, a seal leg of feet vertical height would have to be provided on line 16 to introduce the material against the 20 pounds difierential pressure between the bottom of vessel 38 and the bottom of the dilute-phase lift leg. The steam requirement would be 30 to 40 thousand pounds per hour.

When using the automatic intermittent sealing and lifting device disclosed in this invention no sealing leg is required below the bottom outlet connection of vessel 38 and the solids concentration in the lift leg may be increased to more than 20% or even to gravity packed condition of maximum solids density by using differential pressures ranging from 50 to 100 pounds per square inch or greater. The steam requirements are only about 5,000 to 8,000 pounds per hour as compared with 30,000 to 40,000 pounds per hour in the previous case. The greatly decreased steam velocities in the lift leg practically eliminate the attrition loss on the recirculating solids, the equipment cost is only a small fraction of that required for the mechanical elevators and the operating costs are greatly decreased over that of the low differential pressure conventional lift.

In the case of a continuous coking operation such as described in Patent 2,561,334, dated July 24, 1951 of which I am co-inventor, in which petroleum coke is employed as a circulating solids material, the efliciency .of the new type lifting and sealing device is also very attractive for coke having an average particle size as great as /2 inch may be economically handled since the high solids concentration lift operates more efficiently on materials having a rather wide range of individual particle diameter.

In accordance with the modified form of construction shown in Fig. 3 the vessel 50 may be at the lower end of a cyclic system and provides for the passage of solids through a line 52 and control valve 53 into a lock chamber 56 as described in my copending application, Serial No. 252,306 filed October 20, 1951, now Patent No. 2,729,190. The lock chambcr56 serves as a temporary reservoir whereby the solids may be delivered from the low pressure vessel 50 which may be a reheater, to the high pressure lift chamber 58 through the valve 60 without causing pressure fluctuation in the rest of the systern. The particle level in the vessel 50 and in the lift chamber 53 will fluctuate slightly with the intermittent delivery of solids to and from the lock chamber 56.

The lock chamber 56 is provided with a steam or vapor line having valve 62 which will be operated by a suitable timer 65 which in turn cyclically opens and closes the valve 53, as well as the valve 60. The controller will also control a vent valve 64 for cyclic depressuring of the chamber 56. The lift chamber 58 is never allowed to completely empty, so there is a continuous supply of solids for the mass flow lift line 68. In operation the sequence is as follows:

Starting the cycle with vessel 56 depressured to the same pressure as vessel 50 and ready to receive solids from vessel Stl; valves 60, 67., 53 and 66 are closed. Valve 64- is open. The cycle timer 65 then opens valve 53 and holds it open until after lock vessel 56 has completely filled with solids. The timer then closes valves 53 and M and then opens valve 62 to pressure the lock vessel. When this lock vessel is at the same pressure as the lift vessel d, as determined by time interval or by pressure interlock on the timer circuit, the timer closes the pressuring valve 62 and then opens valves 60 and 66, allowing the solids to flow down into the lift vessel 58 and allowing the gas displaced by the solids to flow back up to the lock vessel 56 thru the balancing line valve 66. This prevents this displacement gas from flowing counter to the solids in valve 60 and retarding the filling of the lift vessel. Valve 60 remains open for a period longer than that required for vessel 58 to fill completely. The timer then shuts valves 6d and 66. Valve 67 is at all times introducing gas or vapor into lift vessel 58 as required to hold this vessel at essentially constant pressure. When valves 60 and 66 have been completely closed, the timer opens depressuring valve 64 and the cycle of operations has been completed.

The various valves 18, 53 and 60 are preferably of the type shown in Fig. 4. In such construction, the valve body '70 has an inlet flange 71 surrounding the inlet passage 72 which may be provided with a liner 73. The body of the valve below the end of the liner '73 is enlarged to form a particle receiving chamber 74 which extends to the outlet flange 75. The valve shut off plate 76 is carried by the valve plate operator 77 which has a rod portion which extends out of the valve body through a stuffing box generally indicated at 78 and is operated by pneumatic or hydraulic piston means not shown in this figure.

The valve shut on plate 7 6 is preferably provided with a spring 82 surrounding its centering stem 83 which ends to force the plate against the edge of the liner '73.

The valve bonnet 79 which carries the stutfing box 78 is preferably provided with gas or steam inlet openings 80 and 8]].-

As heretofore mentioned, the valve is sequentially closed to shut off particle flow through the inlet 72 and as the pressure on the lift chamber below the outlet 74 increases to accomplish the desired lifting of the particles, the valve plate 76 becomes a positive gas seal preventing any appreciable gas flow back into the inlet. As a result, the inlet leg 52 of Fig. 3 need only be a few feet long although there may be a pressure difference between chambers 5d and 56 of from fifty to one hundred pounds or more. The alternative construction of a seal leg of one hundred feet or more indicates the economy of the construction.

It .will be appreciated too, that the valve plate 76 moves through the top of the pile of repose of particles. The valve body has the enlarged body section 74a to allow completely free movement of the valve plate and permit any. particle displacement necessary.

A valve of this type has been found entirely successful in the short cycle cut off operations over years of continued use and not only is there a quick and positive particle cut off but there is the desired gas seal. Replacement of the inlet liners 73 also permits ready maintenance.

A modified valve construction shown in Fig. 6 has also been used successfully on pilot scale operations. In this case, the first valve 90 is identical to the second valve 91 to which it is attached in the arrangement of first valve outlet discharging to second valve inlet. The valve operators, not shown, are interconnected to a controller such as the controller 65 which assures the relatively opposite positioning of the valve cut off plates 9?. and 93, as shown, the cut off plate 92 being open, and the cut off plate 93 being closed. There is thus a free gravity flow of particles into the first valve inlet 94, through and partially filling first valve body 95, and thence into second valve inlet 96. After the desired interval, valve cut off plate 92 moves to the closed position, pressure may be applied to the first valve body through the gas or steam inlet 97 or 97a which will be sufiicient to displace the particles through the second valve outlet 98 and through the connecting lines such as the lift leg 63 shown in Fig. 3.

It will thus appear that the valve bodies serve the purpose of the lock chamber 56 shown in Fig. 3 which is possible when the amount of material and the flow cycle is such that an adequate body of catalyst or other contact particles can be moved intc the valve body. With the large commercial units handling hundreds of tons of contact particles per hour however, the lock chamber construction of Fig. 3 is preferred.

As previously mentioned, the valve bodies are provided with gas or steam purge inlets such as at which aid in cooling the valve when operating on. hot material.

My invention is applicable to the handling of any finely divided solids material between a low pressure Zone and a high pressure zone in which loss of high pressure vapors are to be avoided. It thus makes other processes economically feasible when vapors or gases are to be used as the transmitting force.

While I have shown and described a preferred form of embodiment of my invention, I am aware that modifications may be made thereto and I therefore desire a broad interpretation thereof taken in connection with the attached claims.

I claim:

1. A continuous, closed, contact system having a contacting chamber adapted to receive a granular contact particle mass, said chamber having a fluid inlet and a fluid outlet for the contacting medium, a pressure lift chamber below the contacting chamber, an outlet conduit from said contacting chamber communicating with said pressure chamber, a valve in said conduit, said valve having a recess below the inlet portion, a valve member in said valve movable transverse to the flow of particles in said outlet conduit and into said recess whereby on shut off, the particles will be laterally displaced from the valve inlet portion, means to movably support said valve member for movement transverse to said flow cut off movement, means to apply a gas under pressure to said pressure lift chamber, said gas pressure causing said valve member to move toward and gas seal the solids particle conduit inlet, an elevated disengaging hopper, a lift conduit from said pressure lift chamber to said disengaging hopper, a return conduit from said disengaging hopper to the inlet of said contacting chamber, and a valve in said return conduit restricting the outlet of particles, whereby a level of particles may be established controller is provided to sequentially move the valve cutoff plates alternately in said valves.

References Cited in the file of this patent UNITED STATES PATENTS Domina Nov. 6, 1934 Schaub Mar. 19, 1935 Lefler Feb. 13, 195 

